I don't like slices in D

[Vitali]

On Thursday, 17 October 2013 at 19:05:32 UTC, Jonathan M Davis 
wrote:
> before incrementing dSlice's length, it'll print out 0. dSlice 
> can't grow in
> place, because if it did, its new elements would overlap with 
> those of dArr;
>
> dArr -> [10, 11, 12]
> dSlice -> [10, 11]

Well this is only one part that makes no sense in my eyes. I 
thought the slices should be overlaping.

Here, step by step:

void main() {
   int* arrPtr1;
   int* arrPtr2;
   int[] arr = [1, 2, 3];

   arrPtr1 = arr.ptr;
   arr.reserve(5);     // reserve capacity
   arrPtr2 = arr.ptr;
   assert(arrPtr1 != arrPtr2); // ok, this makes sense
   assert(arr.capacity==7); // ok, this makes not so
   // much sense, but it's bigger than 5,
   // I guess it's ok

   // I reserved extra capacity. I got more
   // than I needed, but ok.


   arr ~= 4; // appending an element
   assert(arr[3]==4);
   arrPtr1 = arr.ptr;
   assert(arrPtr1==arrPtr2); // no reallocation,
   assert(arr.capacity==7); // good

   // I have enough capacity to append an
   // element; everything went fine


   arr.length++;
   assert(arr[4]==0 && arr.length==5);
   arrPtr1 = arr.ptr;
   assert(arrPtr1==arrPtr2); // still no reallocation,
   assert(arr.capacity==7); // very good

   // Also the direct manipulation of
   // the length works, as long as a
   // value is assigned that is bigger
   // then the length.


   arr.length--;
   arrPtr1 = arr.ptr;
   assert(arrPtr1==arrPtr2); // good, but..
   assert(arr.capacity==0); // <- WHY ??

   // after the length is reduced the
   // capacity is set to ZERO, this will
   // cause the array to be reallocated when
   // the length is increased by next time,
   // but what is the purpose of this?


   arr.length++;
   arrPtr1 = arr.ptr;
   assert(arrPtr1!=arrPtr2); // different arrays now!
   assert(arr.capacity==7); // yes, as expected
}